The influence of Cryptocotyle lingua (Digenea:Platyhelminthes) infections on the survival and fecundity of Littorina littorea (Gastropoda:Prosobranchia); an ecological approach

This study considers the impact of digenean parasites, especially Cryptocotyle lingua (Creplin) on the survival, reproduction, growth rate and foot colour of Littorina littorea (Forbes and Hanley). An 18 month field experiment demonstrated decreased survivorship of infected snails. A laboratory experiment showed a drastic reduction, but not total cessation, of gamete production in infected females. Infection was found to retard growth and correlate with reduced shell height in some animals. A strong relationship was found between foot colour and infection. The relevance of infection to the population dynamics of L. littorea on the Ythan, and to the Ythan food web as a whole, is considere